Add SDK signing payload inspection utility

[El-swaggerito]

Description

Difficulty: Expert

Type: Feature

Summary

Add a utility that allows consumers to inspect a transaction signing payload before signing.

Current Behaviour

Consumers may need to show users what they are about to sign before the signing action occurs.

Expected Behaviour

The SDK should provide a safe typed summary of the signing payload without exposing unnecessary raw internals.

Suggested Implementation

Create a helper that accepts a prepared transaction or signing request and returns a typed summary including source, operations, memo, network, and fee where available.

Files or Areas Likely Affected

src/transactions/
src/wallet/
src/types/
tests/
docs/

Acceptance Criteria

• A signing payload inspection utility is added.
• The summary includes source, operations, memo, network, and fee where available.
• The utility does not sign or submit transactions.
• Tests cover supported and unsupported payloads.
• Documentation includes a user-confirmation example.

Additional Notes

This supports safer review-before-signing flows.

[Nabeelahh]

Hi maintainer I have thoroughly read the description to this issue and I can resolve this according to the description required ensuring it meet all the acceptance criteria kindly assign..

[grantfox-oss]

🦊 GrantFox — @Nabeelahh has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #163)
2. Your PR will be reviewed by the Axionvera maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@Nabeelahh's PR #329 was approved and merged by @El-swaggerito.

🏆 @Nabeelahh: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (662 total points). Track your full progress on GrantFox.

👏 Great work, @Nabeelahh! Keep contributing to Axionvera.